Xbox (beta) Administrator approval required for installation.

Sorry to hear it. Requiring Administrator approval for installation suggests that's how your computer is set up. You would need to use the Beta App as an Administrator. Just look for Xbox Beta in your Start Menu and right click on it. Select Run As
Administrator

Many people have the problem where they cannot install any game that "requires administrator approval". I dont know if they consider this a bug or a feature in the Xbox (Beta) app.

When the xbox app goes to install a game, something prevents the standard administrator approval window from popping up to alllow the user to approve the install. After about 60 seconds, the installer times out and reports an error, as seen in the image
posted by Fredric. If a game does not require the admin approval window popup, the installation succeeds.

Do you have already try this?:

Fix for Game Pass for PC Admin Error (0x80070005)

In my case I could not even uninstall the latest windows update, I got an error, and I think I tried that fix and it did not work either, I think the best thing in your case is to wait for a solution from windows update because reinstalling windows is not
for everyone, in my case I am satisfied because it solved other additional errors I had besides being able to download the Xbox Game Pass games normally, I wish you good luck with that and I hope an official solution will come out soon

I tried all the various methods listed without any result ... the only one that had temporarily solved the situation was the uninstallation of the last windows update ... just that when I restarted the PC the problem was again present ... . so if I reinstalled
the update I was able to download again .... until the next reboot where the admin approval issue came up again ... the only thing I didn't do (and won't do) is to reinstall windows. so i hope a corrective patch will be released as soon as possible ... thanks
... regards

I do not intend to say that all people have reinstalled windows to solve the problem, some have solved it for example by uninstalling Avast, others uninstalling a Windows update, others have been solved with the latest updates, resetting windows store, etc
(by the way none of this worked for me)...

I only say that in my case I got tired because I did not find any solution after many hours of research and I opted finally for a clean installation, I do not have much free time so I reinstalled Windows 10 and fixed the problem and it took me one day to
install drivers, apps and everything else, it's just a suggestion if someone can not find a solution, probably Microsoft soon release an update that solves these problems, but it is an uncertainty.